Integrated fluidic flow network for fluid management

ABSTRACT

An apparatus and method is presented for the management of fluid flow utilizing different adjacent wettability regions to form a fluidic network structure on a substrate. The fluidic network structure may include liquid-absorptive fluidic channels, where the fluid can flow within these channels and be removed from the substrate. Fluid can be moved by gravitational force, compression force, capillary force and surface tension force.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. §111(a) continuation of PCTinternational application number PCT/US2015/021889 filed on Mar. 20,2015, incorporated herein by reference in its entirety, which claimspriority to, and the benefit of, U.S. provisional patent applicationSer. No. 61/969,040 filed on Mar. 21, 2014, incorporated herein byreference in its entirety. Priority is claimed to each of the foregoingapplications.

The above-referenced PCT international application was published as PCTInternational Publication No. WO 2015/143411 on Sep. 24, 2015, whichpublication is incorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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INCORPORATION-BY-REFERENCE OF COMPUTER PROGRAM APPENDIX

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NOTICE OF MATERIAL SUBJECT TO COPYRIGHT PROTECTION

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BACKGROUND

1. Technical Field

The technology of this disclosure pertains generally to fluidmanagement, and more particularly to the management of fluid flowutilizing different adjacent wettability regions to form a fluidicnetwork structure on a substrate.

2. Background Discussion

Perspiration is the primary means of thermoregulation for the human bodyduring which sweat (mainly composed of water) is secreted on the skinand evaporation of the fluid removes the heat from the surfaceunderneath. Without efficient sweat removal during intensive activity,accumulated sweat can drastically increase the humidity levelsurrounding the skin, resulting in a very uncomfortable feeling.Activewear which uses highly-wicking fabric has been the currentstandard solution for removing sweat from the body. These wicking-basedfabrics utilize the capillary action of the fibers to absorb moisture.They depend on evaporation to dissipate the moisture and dry the fabric.However, serious problems exist in this wicking-evaporation moistureremoval mode. For example, after being completely hydrated, the weightof the saturated fabric will increase and the wicking process willcease. This saturated fabric can result in an uncomfortable feeling onskin. The gas permeability of the fabric will also decrease as themoisture blocks the air channel between the fibers of fabric.

The current sports apparels are composed of liquid-absorptive fabricthroughout the whole garment, with interconnected hydrophilic regionsfor absorbing perspiration. Once a portion of the garment touchesperspiration, it quickly absorbs the moisture and spreads it over alarge area of the garment. Due to the capillary-wicking principle, themoisture will be transported from the wet area to the dry area of theshirt until the whole garment is saturated. This mechanism workssatisfactorily with small amounts of perspiration but performs poorlywhen the wearer perspires heavily. When the wearer rapidly perspires,the whole garment becomes equally wet, heavy, sticky and uncomfortable,even on the regions of the body where the garment barely touches theskin. The saturated fabric then blocks the vapor transport route fromthe skin to the environment and inhibits the evaporative cooling on thebody's surface. Moreover, the regions of the body that rarely touch thefabric can experience an unpleasant chill due to the evaporation of themoisture on the saturated shirt that is in contact with the skin.

One cause for the aforementioned problems is that when designing thesetypical garment structures, the fact that the human body has varioussweat rates on different sections of the body is overlooked. The drynessof the fabric over the area where sweat is slowly secreted orinfrequently touches the garment (e.g. chest, abdomen and lower back) issacrificed in order to absorb the sweat from heavy perspiration regions(e.g. head, neck, and upper back). For example, the front panel of ashirt is often quickly saturated by the perspiration running down fromthe head and neck regions, instead of the chest and abdomen regionswhere the fabric mainly covers. Similarly, the lower region of shirt'sback panel, though infrequently in contact with the skin, is oftensaturated by the sweat running down from the head/neck and upper backregion where sweat is generated more quickly and skin is more closelycompressed with the garment. These fabrics do not manage moisture in away that is comfortable for the human body.

Newly developed high-tech fabrics, including NanoTex® and wickingwindow, try to solve this problem by modifying the inner surface layerof the fabric. For example, the NanoTex® invention modifies the innersurface layer (the surface in contact with a moisture producing surfaceor skin) of the fabric to be less hydrophilic than the outside. As aresult, the moisture will tend to be transferred to the outside surfacelayer of the fabric and evaporate. The wicking window fabric utilizes asimilar idea. The inner surface layer of the fabric is modified to forma discontinuous hydrophobic pattern. Consequently, the wet area innersurface layer the fabric is reduced and more moisture is transferred tothe outside of the fabric to be absorbed. However, critical problemsstill exist in these fabrics. There is reduced gas permeability and ahuge increase in weight when the fabric absorbs the liquid.

Another example fabric utilizes a 3D knitting structure (X-bionic®) tocreate a curved structure of the fabric to reduce the contact area ofthe fabric and improve the gas flow. However, the total area of thefabric is increased because of the curving. The increased area resultsin an additional increase in the weight change when the fabric becomeswet compared with normal fabric.

Another example is Dri-release® fabric which utilizes a blend ofhydrophilic and hydrophobic fibers to resolve the common problem ofnatural fibers. However, the final outcome is still a hydrophilic fiberthat does not enable the transport or removal of fluids when made intofabrics.

BRIEF SUMMARY

An apparatus and method are described that utilize different wettabilityregions to form a fluidic network structure for fluid management.According to one embodiment of the described technology, the fluidicnetwork structure includes fluidic channels that are formed by thedifferent wettability regions within a substrate. These fluidic channelnetworks can be designed like a siphon system within the substrate andcan utilize primarily gravitational force to transport and removemoisture, instead of by capillary absorption. In some situations, thesurface tension force or compression force exerted by the fabric on themoisture will facilitate fluid transport.

In one aspect of the presently described technology, the substrateincludes different wettability regions that are liquid-absorptive andform a wettability gradient. When fluid contacts the substrate, thefluid moves along the gradient from the less liquid-absorptive regionsto the more liquid-absorptive regions.

In another aspect of the present technology, the substrate includesfluidic channels that are formed by adjacent liquid-absorptive andliquid-repellent regions. Fluid movement into the liquid-absorptivefluidic channels can be facilitated by compression force generated bythe liquid-repellent regions.

Further aspects of the technology described herein will be brought outin the following portions of the specification, wherein the detaileddescription is for the purpose of fully disclosing preferred embodimentsof the technology without placing limitations thereon.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The technology described herein will be more fully understood byreference to the following drawings which are for illustrative purposesonly:

FIG. 1A is a schematic front view of a liquid-absorptive region forminga channel within a liquid-repellant region of a substrate, according toan embodiment of the present description.

FIG. 1B is a schematic side sectional view of the material in FIG. 1A incontact with skin.

FIG. 2A is a front view of examples of liquid-absorptive regions formingchannels in different shapes.

FIG. 2B is a front view of a liquid-absorptive region that extends theentire length of the substrate.

FIG. 2C is a front view of two fluidic channels on a substrate where themajority of the area is still liquid-absorptive.

FIG. 2D through FIG. 2F are front view diagrams of examples of fluidicchannel networks.

FIG. 3A is a front view of a fluidic network configured to collectmoisture from a wide area and carry it to a center dripping point.

FIG. 3B is a front view of a fluidic network configured to collectmoisture from a wide area and carry it to side dripping points.

FIG. 4A and FIG. 4B are diagrams of examples of how fluidic channels maybe formed into shapes, specifically into heart shapes, according to anembodiment of the present description.

FIG. 5A through FIG. 5C are diagrams of different dripping point shapes,according to embodiments of the present description.

FIG. 6A is a front view of a liquid-absorptive channel where the bottomof the channel is covered by a liquid-repellent layer.

FIG. 6B is a side sectional view of the material in FIG. 6A.

FIG. 6C is a front view of a liquid-absorptive channel where the bottomof the channel is exposed, as it would be on the outer surface layer ofthe substrate.

FIG. 6D is a side sectional view of the material in FIG. 6C in contactwith the skin showing fluid flow paths.

FIG. 7A through FIG. 7C are diagrams that illustrate an embodiment inwhich the inner surface layer (layer in contact with a moistureproducing surface) of the material (FIG. 7A) has more liquid-repellentregion area coverage than the outer layer of the material (FIG. 7C).FIG. 7B is a cross-sectional view of the fluidic channel design of FIG.7A.

FIG. 8A is a front view of the inner surface layer of a material withliquid-absorptive circles that penetrate through the substrate andconnect to the material's outer layer fluidic channel network.

FIG. 8B is a diagram of the cross-section view of the fluidic channeldesign of FIG. 8A.

FIG. 8C is a front view of the outer layer's fluidic channel network ofthe material shown in FIG. 8A and FIG. 8B.

FIG. 9A is a front view of the inner surface layer of a material withliquid-absorptive circles that penetrate through the substrate andconnect to the material's outer layer fluidic channel network. In thisembodiment, the shape of the channel is abstract instead of rectangular.

FIG. 9B is a diagram of the cross-sectional view of the fluidic channeldesign of FIG. 9A.

FIG. 9C is a front view of the outer layer's fluidic channel network ofthe material shown in FIG. 9A and FIG. 9B.

FIG. 10A is a front view of the inner surface layer of a material withliquid-absorptive circles that penetrate through the substrate andconnect to the material's outer layer fluidic channel network.

FIG. 10B is a cross-sectional view of the fluidic channel design of FIG.10A.

FIG. 10C is a diagram of the outer surface layer's fluidic channelnetwork of the material shown in FIG. 10A and FIG. 10B, where theliquid-absorptive channels on the outer surface layer of the substratehave regions that are narrower than the liquid-absorptive regions thatconnect to the inner surface layer.

FIG. 11A through FIG. 11C are diagrams of an embodiment of the presentdescription in which the outer surface layer of the fluidic channelnetwork pattern is completely covered by a liquid-repellent coating.FIG. 11A shows the inner surface layer, FIG. 11B is a cross-sectionalview of the fluidic channel design of FIG. 11A and FIG. 11C shows theouter surface layer.

FIG. 12 is a front sectional view of an embodiment of a fluidic networkstructure configured to manage the moisture produced by the condensationprocess.

FIG. 13 is a perspective view of an embodiment of a liquid-absorptivefluidic channel that is sandwiched between an inner and outerliquid-repellent layer.

FIG. 14 is a front view that shows different configurations of a fluidicchannel.

FIG. 15A through FIG. 15C are diagrams of one embodiment of the presentdescription where the thickness of the material at the liquid-absorptiveregions on the inner surface layer can be larger and extend outwardfurther than the rest of the material. FIG. 15A is a front view thatshows the inner surface layer, FIG. 15B shows a cross-sectional view ofthe material of FIG. 15A and FIG. 15C shows the outer surface layer ofthe material.

FIG. 16A through FIG. 16C are diagrams of an embodiment of the presentdescription with liquid-repellent supporting structures. FIG. 16A is afront view showing the inner surface layer of the material, FIG. 16Bshows a cross-sectional view of the material of FIG. 16A and FIG. 16Cshows the outer surface layer of the material.

FIG. 17A is a cross-sectional view of an embodiment of the presentdescription where the liquid-repellent supporting structures arepositioned on the outside of the substrate material to enable theaddition of a dry layer for separation between the liquid-absorptivechannel and the additional layers of clothes people may put on theoutside of the fluidic channels.

FIG. 17B is a front view of the outer surface layer of the embodimentshown in FIG. 17A.

FIG. 18A through FIG. 18D are diagrams showing how multiple layers ofmaterial can also be combined to form the fluidic network structure orprovide additional functions to the basic fluidic network structure.FIG. 18A is a front view of the inner surface layer of the material(substrate with the fluidic network structure). FIG. 18B is a sidecross-sectional view of the material shown in FIG. 18A. FIG. 18C is aside cross-sectional view of a slightly different alternative for theembodiment of FIG. 18A where the partially liquid-repellant region canbe replaced or enhanced by a film made of completely liquid-repellantmaterial which can be closely attached to the back of the fabric usingadhesive to prevent the fluidic flow from touching the skin. FIG. 18D isa front view of the outer surface layer of the material, according to anembodiment of the present description.

FIG. 19 is a front view of an embodiment of the present descriptionwhere a region of the fluidic channel network is connected to a patch ofabsorptive material that can collect moisture and prevent it fromdripping off of the material.

FIG. 20 is a front view of an embodiment of the present descriptionwhere the dripping point of a liquid-absorptive channel is a movingstructure that can switch the dripping point to a moisture absorptivecollection region.

FIG. 21A is a diagram of a liquid-absorptive channel configured toutilize surface tension-driven flow, with an increasing width from oneend to the other, according to an embodiment of the present description.

FIG. 21B is a diagram illustrating the direction of the fluid flow forthe fluidic channel embodiment shown in FIG. 21A.

FIG. 22A is a diagram of a substrate with a liquid-absorptive regionsurrounded by a less liquid-absorptive region to form aliquid-absorptive gradient.

FIG. 22B is a diagram illustrating the direction of the fluid flow forthe fluidic channel embodiment shown in FIG. 22A.

FIG. 23A and FIG. 23B are images of a small piece of fabric with theintegrated fluidic network structure. FIG. 23B shows the inner surfacelayer of the fabric. FIG. 23B shows the outside surface layer of thefabric with a droplet at the dripping point.

FIG. 24 is a schematic diagram of an example of how the fluidic networkstructure can be constructed by printing a liquid-repellent coatingpattern onto a liquid-absorptive substrate using a screen roller.

FIG. 25A is a top view that shows how the material's outer surface layerchannel pattern is printed using a screen roller, which penetrates thesubstrate completely to form the fluidic channel structure.

FIG. 25B is a side view of a close-up of the material after printing theouter layer channel pattern.

FIG. 26A is a diagram that shows how the material's inner surface layerchannel pattern is printed using a screen roller which penetrates thesubstrate half way to form the fluidic channel structure.

FIG. 26B is a diagram of a close-up of the material after printing theinner surface layer channel pattern.

FIG. 27A is a diagram of the outer layer of a knitted fluidic channelstructure according to an embodiment of the present description.

FIG. 27B is a diagram of the inner surface layer of a knitted fluidicchannel structure according to an embodiment of the present description.

FIG. 27C and FIG. 27D are diagrams of close-up top views of the knittedfluidic channel structure according to an embodiment of the presentdescription.

FIG. 28A through FIG. 28C are graphs that show how channel length, widthand textile porosity, respectively, can influence the flow rate of thefluidic network system.

FIG. 29 is a graph that shows how the shape of the dripping point caninfluence the flow rate of a particular fluidic channel network.

FIG. 30A is a front view of the fluidic channel pattern used on theouter surface layer of the fabric sample that was compared to a fabricsample with no fluidic channel networks for fluid management.

FIG. 30B is a front view of the fluidic channel pattern used on theinner surface layer of the fabric sample that was compared to a fabricsample with no fluidic channel networks for fluid management.

FIG. 31 is an image comparing a conventional moisture-wicking polyesterfabric sample and a fabric sample with fluidic channel patterns afterapproximately 10 seconds of water flowing down the fabric samples.

FIG. 32A is a diagram of a condensation control material with a fluidicchannel network according to an embodiment of the present description.

FIG. 32B is an image of a condensation control material with a fluidicchannel network collecting moisture according to an embodiment of thepresent description.

FIG. 33A and FIG. 33B show images of the font and back, respectively, ofa shirt fabricated with fluidic channel networks that are repeatedthroughout the garment.

FIG. 34A and FIG. 34B depict front and back schematic views of shirtsthat illustrate how the fluidic channels on a shirt may be arranged sothat the formation and dripping of the droplets become unobvious.

FIG. 35A is a diagram of the front side of a shirt with oneliquid-absorptive region that begins at the collar and extends to thebottom of the shirt and two liquid-absorptive regions on either side ofthe shirt that begin at the shoulders and extend down to just below themiddle of the shirt, all of which are separated by liquid-repellentregions.

FIG. 35B is a diagram of the back side of a shirt with an upperliquid-absorptive region and a middle liquid-absorptive region.

FIG. 36A is a diagram of the front side of a shirt with a middleliquid-absorptive region which extend from the collar to the bottom ofthe shirt and two side liquid-absorptive regions.

FIG. 36B is a diagram of the back side of a shirt with two mainliquid-absorptive regions.

FIG. 37A is a diagram of the front side of a shirt with the same channeldesign as the shirt in FIG. 36A with the addition of fluidic channels onthe sleeves of the shirt.

FIG. 37B is a diagram of the back side of a shirt with the same channeldesign as the shirt in FIG. 36A with the addition of fluidic channels onthe sleeves of the shirt.

FIG. 37C is a diagram of the side view of a shirt with the same channeldesign as the shirt in FIG. 36A with the addition of fluidic channels onthe sleeves of the shirt.

FIG. 38A and FIG. 38B are diagrams of the front and back, respectively,of a shirt with a bottom liquid-absorptive panel and two sideliquid-absorptive panels.

FIG. 38C is an image of the shirt described in FIG. 38A with theliquid-absorptive panel on the bottom shown collecting the sweat fromthe wearer after exercise.

FIG. 38D is an image of the shirt described in FIG. 38A and FIG. 38Bwhere the side panels are shown collecting the sweat from the wearerafter exercise.

FIG. 39A and FIG. 39B show a diagram of the front and back,respectively, of a shirt with a liquid-absorptive region which coversboth the collar and chest area and extends to the side dripping pointsof the shirt while the abdomen region is kept liquid-repellent.

FIG. 40 is a diagram of an example fluidic channel network in the shapeof a tree patterned on the front outer surface layer of a shirt.

FIG. 41A is a diagram of the front side of a shirt that has threeregions of liquid-absorptive channels separated by liquid-repellentregions.

FIG. 41B is a diagram of the back side of a shirt that has four regionsof liquid-absorptive channels separated by liquid-repellent regions.

FIG. 42A is a diagram of an example fluidic network structure as appliedto the waistband of a pair of shorts.

FIG. 42B is an image of an example fluidic network structure as appliedto the waistband of the front of a pair of shorts.

FIG. 42C is an image of an example fluidic network structure as appliedto the waistband of the side of a pair of shorts.

FIG. 43 is a diagram of an example fluidic network structure as appliedto the waistband and upper area of a pair of shorts.

FIG. 44 is a diagram illustrating another fluidic channel networkconfiguration where fluid-absorptive channels cover the shorts totransport the sweat to the sides of the shorts and drip it away via thedripping points.

FIG. 45 is a diagram of one embodiment of a sock with a fluidic networkstructure that has fluidic channels that carry the sweat running downthe leg to the sides of the sock and drip it away via dripping points.

FIG. 46A shows a front view of one embodiment of a headband with afluidic network structure.

FIG. 46B through FIG. 46D are images of the embodiment shown in FIG.46A.

FIG. 47 is a diagram of one embodiment of a cycling garment with afluidic network structure.

FIG. 48A is a perspective view of one embodiment of a four cornered tentwith a fluidic network structure.

FIG. 48B is a perspective view of one embodiment of a cylindrical tentwith a fluidic network structure.

DETAILED DESCRIPTION

Wettability is a characterization of the interaction between the surfaceof a material and a liquid. Based on the wettability differences withina single material, when liquid contacts the material's surface, it willeither be absorbed or repelled by the material's surface. This can besummarized as two states of wettability: liquid-absorptive andliquid-repellent. The liquid wettability of a material's surface isrelated to the contact angle of the material's fiber for a certainliquid, α, geometry of the porous structure, characterized by theaverage pore radius, r (note that for a fabric structure, the poreradius can be estimated as the distance between two adjacent fiberpeaks) and the property (surface tension, γ and liquid pressure, P_(L))of the liquid on it. Either absorption or repellency of the liquid canbe roughly determined by a critical value, S, which is called the valueof wettability:

$\begin{matrix}{S = {P_{L} + \frac{2\gamma \; \cos \; \alpha}{R}}} & \left( {{Eq}.\mspace{14mu} 1} \right)\end{matrix}$

If S>0, the liquid will be absorbed by the fabric. If S<0, the liquidwill be repelled by the fabric. The larger the number, the moreliquid-absorptive the material. Equation 1 provides a way to generallyand quantitatively compare the wettability of two surfaces. From theabove relationship, it is shown that the wettability is indeed acombination of these parameters and is different depending upon a givencondition.

It should be noted that the definition of wettability is much broaderand more accurate than the conventional definitions of a “hydrophilic”and “hydrophobic” material. Usually, a material with a contact angle ofwater smaller than 90° is called hydrophilic and above 90° is calledhydrophobic. This phenomenon can be understood from the equation above:when a is smaller than 90°, cos α is larger than zero and S is usuallylarger than zero (unless the liquid pressure P_(L) is much lower thanzero), which means a liquid will be absorbed into the material. However,even when the contact angle is above 90° (hydrophobic) and the righthand side of the equation is negative, a small amount of pressurizedwater or a micro tiny water droplet with a large P_(L) is still likelyto be absorbed by the material.

For example, the failure of water repellency has been observed when ahigh-speed pressurized water stream is used to impact a liquid-repellentsurface, where the material holds the water and becomes“liquid-absorptive.” Therefore, “liquid-repellent” and“liquid-absorptive” will be consistently used herein to describe theoverall wettability of the material structure.

It should be noted that the wettability of the material should not beviewed as a fixed structure or contact angle of the material, but as aspecific character of the material's structure under a given range ofliquid properties and conditions. For example, a liquid-repellent regionfor sweat control might become a liquid-absorptive region forcondensation collection since the liquid pressure is larger in thelatter condition.

Referring more specifically to the drawings, for illustrative purposes,embodiments of the apparatus and method for managing fluid flow usingmaterials with liquid-absorptive and liquid-repellent (or lessliquid-absorptive) regions that form a fluidic network structure aredescribed herein and depicted generally in FIG. 1A through FIG. 48B. Itwill be appreciated that a structure depicted in multiple figuresthroughout the description is given the same reference number. It willalso be appreciated that the methods may vary as to the specific stepsand sequence without departing from the basic concepts as disclosedherein. The method steps are merely exemplary of the order that thesesteps may occur. The steps may occur in any order that is desired, suchthat it still performs the goals of the claimed technology.

FIG. 1A is a schematic diagram of one embodiment 100 of aliquid-absorptive region 102 forming a channel 118 within aliquid-repellent region 104 of a substrate 106. The wetting contrastbetween these two regions will form a virtual channel 118 to confine theliquid flow inside the liquid-absorptive region 102, while theliquid-repellent region 104 remains dry. Many fluidic channels 118 canbe formed on a particular substrate 106 to form fluidic networkstructure designs (siphon networks). For the most efficient fluidremoval, the orientation of the liquid-absorptive channels 118 withinthe fluidic network design should not be completely horizontal whenbeing used. The bottom lowest gravitational region of the channel 118 iscalled a dripping point 108. The dripping point 108 is generally wherethe liquid-absorptive region 102 and adjacent liquid-repellent region104 meet at the lowest gravitational point of a channel 118. The fluidflowing down along the length, L, of the channel 118 will accumulate atthe dripping point 108 until the fluid forms a droplet 116 that growsbig enough to fall away from the material. The width, W, of the channelmay vary according a particular application.

As shown in FIG. 1B, when the material (the substrate with a fluidicnetwork structure) is in contact with human skin 110 for example, themoisture 112 on the skin 110 in contact with the liquid-absorptiveregion 102 of the material will be quickly absorbed and will wet thechannel region. Moisture 112 in contact with the channel 118 will becontinuously sucked into the channel 118 due to a siphon-like principlewhere the gravitational force keeps the moisture moving downward 114.This results in a majority of the channel 118 remaining unsaturated. Themoisture 112 will be drawn into the unsaturated part of the channel 118due to the pressure difference.

As a result of this self-sustaining process, the excessive moisture 112that has not evaporated will gradually accumulate at the bottom drippingpoint 108 of the channel 118. Droplets 116 can form at the drippingpoint 108 and will be initially pinned at the dripping point region dueto the hysteresis which results from the large contact angle differencebetween liquid-absorptive and liquid-repellent regions. The droplets 116will keep growing bigger as more moisture is collected. Droplets willdetach and drip off from the surface of the material as gravitationalforce becomes larger than the hysteresis force.

The flow along the channel 118 direction comprises two parts: one is thefree surface flow on the surface of the material and the other is theflow inside of the channel pattern. The flow rate on the outer surfacelayer, Q_(s), and the inner surface layer (the layer in contact with amoisture producing surface) flow rate, Q_(i), of the liquid-absorptivepattern can be characterized by equations 2, 3 and 4 below:

$\begin{matrix}{{\left. Q_{i} \right.\sim\frac{kWT}{\mu \; L}}\Delta \; P} & \left( {{Eq}.\mspace{14mu} 2} \right) \\{{\left. Q_{s} \right.\sim\frac{H^{3}}{\mu}}\frac{\Delta \; P}{L}} & \left( {{Eq}.\mspace{14mu} 3} \right) \\{{\left. \frac{\Delta \; P}{L} \right.\sim\rho}\; g\; \cos \; \theta} & \left( {{Eq}.\mspace{14mu} 4} \right)\end{matrix}$

where k is the permeability of the fabric to fluid, L, W and T are thelength, width and thickness, respectively, of the liquid-absorptiveregion, ΔP is the hydrostatic pressure, H is the thickness of thesurface fluid film, μ is the viscosity of the fluid and θ is the anglebetween the channel's orientation and the vertical (gravitational)direction (the range is 0 to 90 degrees which is completely horizontal).This angle can vary with different orientations of the material duringmotion and should always be calculated with reference to the presentdirection of gravitational force.

The moisture that is not directly underneath the liquid-absorptivepattern can be partly pushed towards the fluidic channel by squeezingfrom the liquid-repellent region 104. This “pushing” transport issignificant if the material is in close and compressed contact with amoisture producing surface, such as human skin for example. This can beseen when the fluidic network structure is applied to apparel and isstretched against skin during motion or worn as a compression garment.During this process, the majority of the moisture 112 is removed by thefluidic network (see FIG. 2D through FIG. 2F) and dripping of the excessmoisture, while the liquid-repellent area remains dry and forms abarrier to block the fluid from flowing underneath.

The moisture-removal enabled by the fluidic network structure on apparelcan maintain the necessary amount of moisture 112 on the skin 110 forcooling by evaporation and allows the vapor to freely pass through thedry area (liquid-repellant region 104) of the material 106. The fluidicchannel structure itself keeps removing the excessive moisture only.This structure provides a combined cooling effect of the wet fabricpattern itself and the evaporation cooling on skin.

Although sweat on skin is used as an example to explain the moisturetransport process of many embodiments of the material, it should benoted that the structure can be applied to a broad range of moisturemanagement applications. This includes removal of moisture on differentsurfaces, removal of condensation, spill control, fuel cell electrodes,etc. The moisture can be water, bio-fluid (sweat, urine, blood, etc.),oil, organic solvents and many others. In addition, the terms“hydrophilic” and “hydrophobic,” are general descriptions of amaterial's affinity for liquid. Use of these terms does not limit thestructure to water-related applications. One can derive the appropriatestructure and material for each situation based on the theory of liquidwettability on fabric aforementioned.

Referring now to FIG. 2A, the shape of the liquid-absorptive region 102(or channel) can be rectangular, triangular, circular, polygon, etc. andis not limited. The shape can be tilted and have various angles, θ. Theliquid-absorptive region 102 can also extend through the entire lengthof the material, as shown in FIG. 2B. Multiple channels 118 can be incontact to form a fluidic channel network to transport the moisture overan area to the dripping point 108. Three examples of fluidic channelnetworks are shown in FIG. 2D, FIG. 2E and FIG. 2F. The location of thechannels 118 on the substrate can be arbitrary. The channel patterns canalso be repeated to cover the whole substrate.

The width of the liquid-absorptive channel pattern can vary depending onthe application of the fluid management system. The length of theliquid-absorptive region 102 or network pattern can be very short or aslong as the length of the material (see FIG. 2B). The ratio of theliquid-absorptive area to the liquid-repellent area is not limited. FIG.2C illustrates two fluidic channels 118 on a material where the majorityof the area is still liquid-absorptive 102.

In one embodiment, shown in FIG. 3A, a fluidic network of channels 118may be constructed to collect a wide area of moisture 112 to a centerdripping point 108. Alternatively, the channels 118 can be constructedso that all of the excess moisture can be divided to the two sidedripping points 108 and drip away, as shown in FIG. 3B.

In another embodiment shown in FIG. 4A, the fluidic channels 118 can beconstructed to be curved lines that form an esthetic pattern, such as aheart shape. Alternatively, different lengths of channels 118 can bepositioned into a patterned shape, as shown in FIG. 4B.

In yet another embodiment, the liquid-absorptive channel pattern can becolored with a different dye on a fabric so that it stands out as adecoration on a garment whether the pattern is wet or dry.

The shape of the dripping point 108 can affect the dripping rate of thefluidic channel network. The dripping point 108 can have a differentgeometry than the channel, which can accelerate or slow the drippingprocess of the fluidic channel network and can also affect the overallfluid removal rate of the fluidic channel network siphoning system. Forexample, a narrow dripping point (in relation to the channel width) willaccelerate the droplet dripping rate of the channel. FIG. 5A throughFIG. 5C show examples of different dripping point 108 shapes. Thedripping point shown in FIG. 5A creates a higher droplet dripping ratethan those shown in FIG. 5B or FIG. 5C.

Though the channel 118 should be liquid-absorptive, the thickness ofthat liquid-absorptive region 102 can be non-uniform throughout thesubstrate. In other words, part of the liquid-absorptive region 102 canbe modified to be less liquid-absorptive or liquid-repellent to furtherreduce wetness of the fabric and promote fluid management.

In one embodiment 600 shown in FIG. 6A through FIG. 6D, the bottomregion 602 of the liquid-absorptive region 102 can be covered by aliquid-repellent layer 604. FIG. 6A shows the inner surface layer of thematerial that would be in contact with the fluid producing surface, inthis example, human skin. FIG. 6B shows a cross-section view of thematerial and illustrates how the bottom region 602 of theliquid-absorptive region 102 (channel) can be covered by aliquid-repellent layer 604. FIG. 6C shows the outer surface of thematerial. FIG. 6D shows how this design can facilitate the accumulateddroplet 116 drip at the bottom of the fluidic channel on the outer layerof the material instead of flowing backward to the gap between the skinand the inner layer of the material. In this embodiment, the length ofthe liquid-repellant pattern is long enough so that the hydrostaticpressure of the liquid inner layer of the material is higher than theLaplace pressure of the outside dripping droplet ΔP₂.

FIG. 7A through FIG. 7C are diagrams that illustrate an embodiment 700in which the inner surface layer of the material 106, shown in FIG. 7A,has more liquid-repellent region 104 area coverage than the outersurface layer of the material, shown in FIG. 7C. The inner surface layer(in contact with the liquid-producing surface) of the material has adiscontinuous liquid-absorptive region 102 in a pattern 702 made up ofsmall circles (or any other shape). These liquid-absorptive regions 102on the inner surface of the material are connected throughliquid-absorptive paths 704 to the outer layer liquid-absorptivechannels 118 of the material, as shown in the cross-section view in FIG.7B. The liquid-absorptive regions 102 forming the pattern 702 on theinner surface layer of the material serve as small inlets that suckmoisture to the outer siphon networks (liquid-absorptive channels 118).The moisture removal rate of this structure from an inner surface layerto an outer layer is strongly limited by the size of the inlet, whichserves as a channel connecting the inner and the outer surface layers ofthe material 106. The larger the size of the inlet, the quicker the flowrate.

The inner surface layer pattern of the material can be as simple ascircles or the pattern can be complex. The size of the pattern can bevaried. The inner surface layer liquid-absorptive pattern can be largeror smaller than the outer layer pattern size.

In the embodiment 800 shown in FIG. 8A through FIG. 8C, the inner layerof the material, shown in FIG. 8A, has 5 mm liquid-absorptive circles802 with a 5 mm space between each circle 802. The uniformly distributedliquid-absorptive pattern ensures an efficient capture of moisture. Theliquid-absorptive circles penetrate through the material substrate andconnect to the outer layer of the material which has a fluidic channelnetwork design that connects the entire liquid-absorptive circle patternon the inner layer of the material. The channel design uses a minimumnumber of channels 118 to connect all of the liquid-absorptive circlesso that the overall wet area on the material is minimized. The outsidelayer channel patterns are also designed so that they can be repeatedover the entire material substrate. FIG. 8B shows a cross-sectional viewof the design. FIG. 8C shows the outer surface of the material. Theouter layer channels 118 are mainly vertical (5.5 mm in width and 5 mmapart) with two 45 degree tilted channels that connect the lines andmerge them into one dripping point 108 at the bottom of the mainchannel.

The embodiment 900 in FIG. 9A through FIG. 9C is a variation of theembodiment shown in FIG. 8A through FIG. 8C. In this embodiment 900, theliquid-absorptive channels 118 are an irregular shape instead ofrectangular and the liquid-absorptive paths are smaller at the innersurface layer (FIG. 9A) and get larger as they go through the thicknessof the material to the outer layer to the fluidic channels 118.

In the embodiment 1000 shown in FIG. 10A through FIG. 10C, theliquid-absorptive channels 118 on the outer layer of the material 106(FIG. 10C) have narrow regions 1004 that are narrower than theliquid-absorptive regions that connect to the inner surface layer 1002.This design can further reduce the wet area of the entire material whilemaintaining a similar transport rate through the liquid-absorptiveregions that connect to the inner surface layer 1002. FIG. 10A shows theliquid-absorptive regions that connect to the outer layer 1002 patternedon the inner surface of the material 106. FIG. 10B shows a cross-sectionview of the embodiment 1000.

Alternatively, a large portion of the fluidic channel on the innersurface layer of the material can be covered by a liquid-repellentcoating. This region of the channel can serve as a rapid transportchannel for the moisture and can prevent any possible liquid leakingback to the inner surface layer of the material. This design can alsoprevent the adhesion of the hydrophilic channel area to the skin andprevent the disruption of fluid flow due to the capillary pressure. Inaddition, the design can also help reduce the unpleasant feeling when alarge amount of fluid is flowing on perspiring skin, such as when thematerial is used as an exercise garment for example. The fluidic channelprovides freedom for the design as well as more control of the directionof the fluid movement.

Similarly, the diagrams in FIG. 11A through FIG. 11C show an embodiment1100 in which the outer surface layer (FIG. 11C) of the fluidic channelnetwork pattern is completely covered by a liquid-repellent coating, asshown in the cross-sectional view in FIG. 11B. The inner surface layerof the pattern can remain constant from the top of the material to thedripping point 108 as shown here or can resemble any of the embodimentspreviously shown or any other patterns suited for a particular need.This provides a region where moisture can contact the channel 118 andflow inside the material but is not visible from the outside of thematerial, as shown in FIG. 11C. This embodiment can be particularlyuseful when made into a compression garment, which will generate contactpressure that pushes the moisture towards the liquid-absorptive region102 patterns. The accumulated moisture can be kept or transported awayby the liquid-absorptive channel 118 structure. Furthermore, thisembodiment solves the problem of having to wear a completelyuncomfortable, liquid-repellent fabric when sweating. It provides afabric design that removes sweat and cools the body, while maintainingits liquid repellency and dustproof characteristic on the outside of itssurface.

This embodiment can also be useful in reducing and managing condensationon the surface of the material. The design 1200 shown in FIG. 12demonstrates one possible embodiment of a fluidic network structure forcontrolling the moisture 1202 produced by the condensation process. Thepattern controls the larger sized droplets that are able to stay on thematerial because of the gap, D, between the liquid-absorptive channels.Any droplet that grows to a size larger than D will be transported awayby the liquid-absorptive fluidic channel and finally collected at thebottom dripping point 108.

In an alternative embodiment 1300 shown in FIG. 13, a completely sealedor closed liquid-absorptive channel 118 can be formed within a materialusing a sandwich structure where two liquid-repellent regions 104 are onthe inside and outside of the material and there is a liquid-absorptiveregion 102 in the middle of the material. This type of structure may behelpful in ensuring a particular direction of fluid flow within thefabric. Moreover, this design can be used to eliminate the flow channel118 appearance on the outside of the material, fabric, garment, etc.Generally, when colored fabrics become wet, they look darker. In thisembodiment 1300, the channels 118 of the siphon network will become moreor less invisible. This closed channel structure helps eliminatepossible visualization of the channel structure. This structure can bepart of a full channel pattern. The water picked up by side channels(not shown) can be fed into this channel and drip away at the bottom ofthis structure.

The channel structure can also be separated by a middle layerliquid-repellent barrier that separates the fluid flow. In other words,a fluidic “diode” structure can be incorporated into the fluidicnetworks to eliminate any reverse wicking flow between adjacent dry andwet collection channels. In the variations shown in FIG. 14, threevertical channels 118 are all separated from the main transportingchannel 118′ by a liquid-repellant gap 1402 of distance d. When themoisture is moving down from one of the vertical channels 118, it willbe accumulated at the boundary where the liquid-absorbent andliquid-repellant regions meet. Once the liquid collects enough toovercome the liquid-repellant gap 1402, it will flow down to thetransporting channel 118′ and be transported away. On the contrary, whenthe transporting channel 118′ is wet, the moisture will not move intothe dry vertical channels 118 due to the liquid-repellant gap 1402. Thisstructure may be used to separate liquid-absorptive regions within onenetwork or between networks. The shape of the gap can be triangular,rectangular, or any other shape to fit a particular purpose. Theposition can be within the transporting channel, above the transportingchannel or at the edge of the transporting channel and is not limited.

In one embodiment 1500, the thickness of the material at theliquid-absorptive regions on the inner surface 1502 can be larger andprotrude outward further than the rest of the substrate material 106, asshown in FIG. 15A through FIG. 15C. This additional thickness orsupporting structure can promote the stability of the liquid-repellentregion 104 and improve its robustness against friction and compressionduring motion. FIG. 15A shows the inner surface layer, FIG. 15B shows across-section view and FIG. 15C shows the outer surface layer of thematerial.

Alternatively, there can be supporting structures 104′ of theliquid-repellant region 104 on the inner surface layer of the material106, as shown in the embodiment 1600 in FIG. 16A through FIG. 16C. FIG.16A shows the inner surface layer of the material, FIG. 16B shows across-section view of the material and FIG. 16C shows the outer surfacelayer of the material. This additional thickness of the liquid-repellentregion can enhance the robustness of the dry regions on the inside ofthe fabric. It also helps reduce the areas of the wet regions that arein direct contact with the skin on the inside of the fabric.

Referring now to FIG. 17A and FIG. 17B, the supporting structures 104′can also be positioned on the outer surface layer of the substrate 106to enable the addition of a dry layer 1702 for separation between theliquid-absorptive channel 118 and the additional layers of clothespeople may put on the outside of the fluidic channels, for example. Thisembodiment 1700 can be varied slightly so that the bottom portion ofmaterial is patterned with liquid-absorptive channels 118 and adhered toanother layer of strong liquid-repellent material (a water repellant drylayer 1702) to provide both outside water repellency (required for agarment such as outdoor rain gear) and inner layer quick moistureremoval capacity that is not limited by humidity or temperature. Thisstructure achieves a “one-directional” moisture transport scheme.Alternatively, there can be supporting structures 104′ on both the innerand outer surface layers of the material (not shown).

It should be appreciated that the density and/or porosity of thematerial can be different at different regions of the material for anyof the embodiments described herein.

Multiple layers of material can also be combined to form the fluidicnetwork structure or provide additional functions to the basic fluidicnetwork structure. In the embodiment 1800 shown in FIG. 18A through FIG.18C, two layers of material substrate are combine. A first layer ofliquid-repellant material 1802 with circle patterns 1804 can be bondedusing adhesive 1806 or other bonding methods to a second layer ofliquid-repellant material 1808 with the outer liquid-absorptive channel118 patterns to form the fluidic network structure. FIG. 18A shows theinner surface layer of the material with the liquid-absorptive circlepatterns 1804. FIG. 18B shows a cross-section view. In a slightlydifferent design, shown in the cross-section view in FIG. 18C, thepartially liquid-repellant region can be replaced or enhanced by a filmmade of completely liquid-repellant material 1810, such as fabric,rubber, plastic, polymer, metal, etc. The material can be closelyattached to the back of the fabric using adhesive 1806 and prevents thefluidic flow from touching the skin. The thickness of this material isnot limited. This film 1810 can be useful in resisting high fluidicpressure and can provide a barrier between the moisture flow and theskin, in cases where the material will be worn as a garment. FIG. 18Dshows the outer surface layer with the fluidic channels.

FIG. 19 shows an embodiment 1900 where a region of the fluidic channelnetwork is connected to a region of absorptive material 1902 that cancollect moisture (e.g. wicking fibers, cotton, superabsorbent polymers,etc.) and prevent it from dripping off of the material. These absorptivematerials will facilitate transport along the system ofliquid-absorptive channels 118 on the material and lock the moistureinside so that it will not drip off of the material. This embodiment isuseful in situations where people do not want the moisture to fall ontothe ground (e.g. when playing indoor basketball, badminton, etc.) orwhen a high flow-rate transport is required.

The dripping point 108 of a liquid-absorptive channel 118 can also be amoving structure as shown in the embodiment 2000 in FIG. 20. Thisstructure can serve as a “switch” where the dripping point of aliquid-absorptive channel can switch the dripping point to a moistureabsorptive collection region. By fixing this structure to the panel ofan absorptive region 2002 on the material, all of the transportedmoisture can be collected. By fixing this point away from the panel ofabsorptive material 2002, the moisture can be dripped away. In oneembodiment, this structure can be an additional liquid-absorptive stripaffixed to the fluidic channel and can have a reversible fixture at thetip, such as Velcro, for easy removal and attachment.

The shape of the liquid-absorptive channel 118 can be specificallydesigned to utilize surface tension-driven flow. The liquid-absorptivechannel 118 may have an increasing width from one end to the other endand can have a triangular shape, for example, as shown in FIG. 21A. Thechannel can be any shape that is necessary for a given purpose, however.Referring to FIG. 21B, when a liquid droplet 116 contacts this region,it will move spontaneously toward the larger width end due to theunbalanced surface tension force at the front and back of the droplet116.

FIG. 22A and FIG. 22B illustrate an alternative embodiment 2200 wherethe material comprises liquid-absorptive regions 2202 that aresurrounded by less liquid-absorptive regions 2204 to form aliquid-absorptive gradient as opposed to a clear liquid-absorptiveliquid-repellant interface. When water contacts the material, water willmove in the direction 2206 from the less liquid-absorptive region to themore liquid-absorptive region due to the wettability gradient as shownis FIG. 22B. This structure does not require liquid-repellentliquid-absorptive contrast but a liquid-absorptive gradient. In otherwords, the fluid will tend to fill the regions that are moreliquid-absorptive. This produces a unidirectional wicking of fluid inthe substrate plane along the more liquid-absorptive region. As aresult, the moisture will be non-uniformly distributed on the surface ofthe fabric, creating a relatively dry region on the lessliquid-absorptive areas. This liquid-absorptive region can also beconstructed to follow the gravity direction so that the gravity forcewill help the moisture to first wick through the more liquid-absorptivepatterns on the material.

FIG. 23A and FIG. 23B are images of a small piece of fabric with theintegrated fluidic network structure shown schematically in FIG. 8Athrough FIG. 8C. FIG. 23B shows the inner layer of the fabric. FIG. 23Bshows the outer layer of the fabric with a droplet 116 at the drippingpoint 108.

The invention may be better understood with reference to theaccompanying examples of how to create the fluidic network structure,which are intended for purposes of illustration only and should not beconstrued as in any sense limiting the scope of the presently describedtechnology as defined in the claims appended hereto.

The fluidic network structure can be constructed by printing aliquid-repellent coating 2400 pattern 2402 onto a liquid-absorptivematerial 2404 using a screen roller 2406, as shown in FIG. 24. There arecurrently several different methods of textile printing available,including flatbed printing, rotary printing, inkjet printing, etc. Anyliquid-absorptive material, including but not limited to cotton, treatedpolyester, nylon, silk, bamboo fibers in woven, knitted or non-wovenstructure, may be used as the material substrate 106. Any of the durableliquid-repellent agents, such as fluorochemicals, silicones, waxes orother similar materials, may be used to create a liquid-absorptivechannel or fluidic network structure.

Some printing methods use various thickeners to keep the ink frommigrating and to maintain a clear or well-defined print. In printing ingeneral, there are a number of variables which can be controlled. Somevariables such as print paste viscosity, amount of print paste applied,roller/wiper pressure, speeds, mesh size of the screen, etc., can beused to control the depth of penetration of the print paste. One way tocontrol depth of ink penetration is to adjust the printing parameters sothat the print paste can completely penetrate through the fabric withoutmerging together. A fluidic network structure can be formed on thematerial substrate as defined by a print screen.

A two-step printing process can be utilized to easily create a materialwith internal liquid-absorptive patterns. FIG. 25A shows how thematerial's outer layer channel pattern is printed using a screen roller2500 which penetrates the material substrate 106 completely to form thefluidic channel 118 structure. A close-up view is shown in FIG. 25B. Forthe material's inner surface layer, a screen roller with the innersurface layer pattern 2600 can be used to print again on the same sideof the material substrate 106, as shown in FIG. 26A and close-up in FIG.26B. By adjusting the printing parameters, the inner layer pattern canbe only half-penetrated through the substrate so that the other side ofthe substrate still maintains the channel pattern. This penetrationneeds to be well-controlled so that the wicking behavior of the outsidechannel is not affected or does not become less liquid-absorptive. Twoscreens can be aligned in the printing process so that the inner surfacelayer inlet pattern lies right on top of the channel pattern. Suchalignment is similar to the multi-color printing process. Similar toprinting multiple colors with precise registration, the liquid-repellentpatterns can be aligned very accurately.

Alternatively, the fluidic channel structure can be created by printingon one side of the material substrate, controlling the penetrationthickness to more than half of the material substrate, and then printingagain on the other side of the material substrate with more than halfpenetration. In this way, a similar fluidic channel structure can becreated but the method requires rotation of the fabric during printing.For a more dense and random pattern for the inner layer design, the twoscreens need not be aligned during the subsequent printing process.There will always be part of the liquid-repellent pattern that lies ontop of the channel pattern.

The printing process can also be used to construct the embodiment 2200illustrated in FIG. 22A and FIG. 22B. The structure can be created bymaking certain regions of the material less liquid-absorptive but notcompletely liquid-repellent.

In another embodiment, a fluidic channel pattern can be formed on fabricwith an inkjet printer. The advantage of inkjet printing is the abilityto control the amounts of ink as well as the penetration powerdigitally, which is more accurate than other printing methods. Theinkjet printer is also more flexible with regard to the printingsubstrate. This process works on raw fabric as well as completed shirts.Similar to the screen printing method, the fabric can be printed in twoways. In one embodiment, the fabric is printed on the front side firstand then on the back side of the fabric. Alignment of the front and backpattern is not necessary if the backside patterns are dense enough tooverlap the front pattern. The amount of ink injected through inkjetprinting is controlled by the printing resolution, inject pressure fromthe head, and the distance between the inkjet head and the substrate. Iftoo much ink is injected onto the fabric, the ink will merge togetherand will not achieve a good image. However, if insufficient ink isinjected onto the fabric, the water repellency of the liquid-repellentregion will decrease due to the incomplete coverage of the ink.Therefore, it is important to control the amount of ink used for eachprint.

Maintaining good resolution as well as good repellency can be achievedusing a repeated printing method. Since the liquid-repellent coating isnot strong without heat treatment, a certain amount of ink can be usedto print the pattern, followed by a second print once the previousprinting has almost dried. If necessary, repeated printing can be used.Since inkjet printing allows control of many parameters, the accuracy ofthis printing method can be very good.

Another method for improving the pattern resolution while maintaining agood soaking of the fibers is to use a “stroke+fill” mode. At first, apattern is printed with only the boundaries of the pattern, and then thefabric is baked to cure the printed boundaries. After the boundaries arecompletely cured, another pattern that fills the empty space inside theboundary of the pattern is printed so that the pattern is completelyfilled. Since the hydrophobic coating defines and limits the spreadingof the ink, more ink can be used on the fabric without worrying aboutthe merging issue.

Yet another method for improving the printing process is by combiningthe inkjet printing with a screen printing method. The screen printingtechnique can apply a very large compression pressure when printing andthe inkjet printing technique can provide a much better control on theprinting penetration. The fabric can first be printed to form a half waypenetrated pattern and then the fabric can go through a screen printingprocess to form the through pattern.

Another method for constructing the fluidic network structure is bystitching separate fabric pieces together into a whole garment. Specificshapes of the liquid-absorptive regions and liquid-repellent regions arepredefined and cut from liquid-absorptive and liquid-repellent fabrics,followed by stitching them together at the boundaries with hydrophilicor hydrophobic threads to form a garment.

Another method is to combine knitting with a printing process. Theknitting process is utilized to create the half-penetratedliquid-repellent structures and liquid-absorptive structures and theprinting is utilized to create the through penetrated liquid-repellentstructures.

The fabric may also be created by knitting liquid-repellant andliquid-absorptive fibers together. One embodiment of the knitted fluidicchannel structure 2700 is shown in FIG. 27A through FIG. 27D. Theliquid-repellant fibers 2702 can be inherently liquid-repellant orachieved by modification of liquid-absorptive fibers 2704. Theliquid-repellant fibers 2702 can be arranged to form theliquid-repellent region on the fabric and knitted with theliquid-absorptive fibers 2704 to form the liquid-absorptive region andchannels.

FIG. 27A shows the outer layer of the knitted material and the innersurface layer is shown in FIG. 27B. FIG. 27C shows the detailedarrangement of the knitted rib structure on the front and back side ofthe fabric composed of liquid-repellant fiber 2702 and liquid-absorptivefiber 2704. FIG. 27D shows how the liquid-repellant fibers 2702 and theliquid-absorptive fibers 2704 may be knitted together.

The material can be created by knitting liquid-repellent fibers to formdifferent pore sizes at the liquid-repellent and liquid-absorptiveregions. The pore size at the liquid-repellent region will be smallerthan at the liquid-absorptive region, which indicates a wettabilitydifference according to Eq. 1. As a result, under high-pressures, liquidwill be pushed to the liquid-absorptive regions with larger pores andwill become wet and absorptive, while the liquid-repellent region staysdry.

Knitting can also be used to construct the embodiment 2200 described inFIG. 22A and FIG. 22B. The material can be constructed utilizingliquid-absorptive fibers such as natural cotton fibers and lessliquid-absorptive fibers such as pure synthetic fibers such as polyesteror nylon. The structure can be achieved using a simple knitting processwith controlled positioning of the two types of yarns into the designedpattern. Alternatively, the fluidic structure can be created by knittingliquid-absorptive fibers to form different pore sizes at theliquid-absorptive and less liquid-absorptive regions. The pore size ofthe less liquid-absorptive regions will be larger than theliquid-absorptive region.

A bonding process may also be utilized to form the fluidic networkstructure. A liquid-absorptive material can be cut into the shape of thechannel pattern and adhered to a liquid-repellant material substrate 106containing holes that allow the moisture to contact theliquid-absorptive channel pattern. Bonding can be achieved throughtechniques including thermoplastic powders, fibers or films.

A stitching process may be utilized to form the fluidic networkstructure on a liquid-repellant material substrate. Liquid-absorptivethreads can be stitched or embroidered on a liquid-repellant materialsubstrate to form the fluidic channels. Alternatively, liquid-repellantthreads can be tightly stitched on a liquid-absorptive materialsubstrate to define the fluidic channels.

Examples and Results

The examples disclosed herein are for illustrative purposes and are notintended to be limiting in any way.

A fabric with an integrated fluidic channel network for force-drivenflow through porous material is described. The driving force of fluidmanagement comes from the hydrostatic pressure of a liquid dropletplaced in a higher position. FIG. 28A through FIG. 28C are graphs thatshow how channel length, width and textile porosity (“white” fabric hasthe largest pore size while “grey” fabric has the smallest pore size)can influence the flow rate of the fluidic system. Similarly, FIG. 29 isa graph that shows how the shape of the dripping point can influence theflow rate of a particular fluidic channel network.

Three different types of knitted fabric materials were compared todemonstrate the different influences on the stability of hydrostaticpressure of the liquid-repellent regions. Two samples of each type offabric (A,B,C) were cut and treated with a liquid-repellent coatingusing an inkjet printer (Freejet 500, Omniprint) loaded with commercialfluoropolymer coating (Aqua Armor, Trek 7). Two different print settingswere used to achieve approximately 50% and 100% penetration of thecoating solution in the fabric. The hydrostatic pressure of each samplewas measured by a lab-built setup. As shown in Table 1, for the sametype of fabric A and B (single-knit jersey), the larger the pore size,the lower the hydrostatic pressure it can withstand before leaking. Thisimplies that the fabric with larger pores is more likely to become wetwhen in contact with moisture, which is predicted by the wettabilitymodel. The hydrostatic pressures of half-penetrated samples also followthe trend of the fully-penetrated printing samples but possess a lowervalue. The interlock structure of fabric C had a similar pore size asfabric A and achieved a higher hydrostatic pressure for both printcoating penetrations. This may be attributed to the less-stretchy andmore stable construction of fabric C using a 100% polyester interlockstructure. This characterization process was shown to be useful whenselecting the appropriate substrate structure for constructing theliquid-repellent region in various applications (e.g. sweat removal,condensation, etc.).

Two fabric samples with the same structure (interlock structure,liquid-absorptive polyester, 175 gm⁻²) were prepared for comparison offluid management utilizing fluidic channels versus moisture wickingfinishes. One of the fabric samples was patterned with a fluidic networkchannel design as shown in FIG. 30A and FIG. 30B. The inner layerpattern, shown in FIG. 30B, penetrated about half of the fabric'sthickness.

In one demonstration, a 6 cm×9 cm piece of the fluidic network fabric3102 and a 6 cm×9 cm piece of the conventional moisture-wickingpolyester 3104 were both fixed on plastic boards as shown in the image3100 in FIG. 31. A syringe pump 3110 was used to feed water at a rate of50 mL/h using two thin tubes 3114. As the water was pumped, the twofabrics presented very different behaviors. The conventionalmoisture-wicking polyester became wet and spread the moisture over theentire surface of the fabric. The fabric with the fluidic channelpatterns quickly conducted the water from the inner surface layer (theback of the fabric) to the outer dripping point where droplets wereformed on the outer surface of the fabric after approximately 10seconds.

After 2 minutes, the conventional moisture-wicking polyester 3104 becamecompletely saturated and kept all of the water inside of the fabric. Themoisture can be identified by the darker color on the fabric square.Conversely, the fabric with the fluidic network 3102 contained themoisture in its fluidic channels 3106. As the moisture collected withinthe fluidic channels 3106 and flowed down the length of the channels tothe dripping point 3108, droplets 3112 continuously dripped off of thefabric and formed a small puddle at the bottom of the plastic board (notshown), demonstrating the fluid management of the fluidic networkstructure.

A more quantitative measurement was also conducted to compare differentcharacteristics of the two fabric samples when wetted by watercompletely, including weight pickup ratio, vapor permeability whensaturated, wet area ratio of the fabric both inside and outside as wellas the drying time. As can be seen from Table 2, for each characteristicparameter, the fabric with the fluidic pattern demonstrated greateradvantages over the conventional moisture-wicking (Control) scheme. Itshould be noted that this data corresponds to the specific fluidicchannel design as shown in FIG. 30A through FIG. 31 and other designsmay possess different values.

A condensation 3208 control fabric was constructed following the design3200 shown in FIG. 32A. The fluidic channel network was designed tofacilitate the removal of all droplets larger than 3 mm.Liquid-absorptive polyester fabric pattern strips 3202 were cut by alaser engraver (VLS, Universal Laser) and bonded to a liquid-repellentsubstrate fabric 3204 (woven hydrophobic polyester) by instant glue.

The fabric sample was placed vertically on a plastic board 3206 and awater vapor flow was generated utilizing a humidifier (model no. 7144,Air-o-Swiss) on the “high” power setting as shown in the image 3208shown in FIG. 32B. After 6 minutes, the vapor was stopped and the weightand drying time of the sample material were recorded. An originalliquid-repellant polyester fabric with the same shape was prepared as acontrol for comparison.

The results are shown in Table 3. The fabric with the fluidic channelscontained 25% less water than the control fabric at the conclusion ofthe experiment.

Moreover, fewer droplets and smaller droplets (higher surface-to-volumeratio) on the sample resulted in a much quicker drying time (110 mincompared with 210 min). During the experiment, it was observed that allof the excess droplets rolled off at the dripping point of the fluidicpattern on the sample fabric. However on the control fabric sample, thedroplets grew to a bigger size (˜4 mm) and ran off of the fabric atrandom locations. These results demonstrate the effectiveness of thefluidic channel structure in managing condensation.

Published research on the sweat rate mapping of the human body duringexercise indicates that the sweat rate at different regions of the bodyvaries dramatically. The sweat rate on the forehead can be 1710 gm⁻²h⁻¹which is about 3 times that of the sweat rate on the middle chest region(546 gm⁻²h⁻¹). This non-uniformity suggests that the fabric over thebody surface should be at different moisture levels during exercise.However, conventional sportswear, constructed with moisture-wickingfabric, absorbs all of the sweat generated on different areas of thebody (including the sweat from head) and then wicks the moisture toadjacent dry areas. This can result in most areas of the shirt becominguniformly saturated even though several areas (including side chest,waist, lower belly, etc.) have slower sweat rates and should remaindrier if only absorbing the sweat underneath of that particular region.

For example, the chest area of a wearer's sportswear can becomesaturated and sticky very quickly during exercise. However, this area ofthe shirt is mainly soaked by sweat generated on the head which flowsdown along the neck to the collar of the shirt and spreads over thechest area of the shirt. Accordingly, FIG. 33A and FIG. 33B show imagesof the front 3300 and back 3302 of a shirt fabricated with fluidicchannel networks 3304 that are repeated throughout the garment.

Since each pattern is separated by a liquid-repellent barrier and theremoval capacity of each unit is independent, the regions with a lowersweat rate 3306 will be kept much drier. The shirt is able to remove thesweat that is generated on the torso by dripping the sweat away at thedripping point 3308 of each fluidic channel network 3304. Such a fabricstructure can be applied to shirts, shorts, pants, tank-tops, sportsbras, underwear, etc.

The geometry and arrangement of the fluidic channel networks can bepositioned to fit the mapping of the sweat rate regions of the body toprovide comfort during exercise. The positioning involves theappropriate arrangement of these networks related to the physiologicalcharacter and comfort of the human body and can even be customized tosuit a particular wearer. Further aspects of the presented technologywill be brought out in the following examples of several categories ofapparel, wherein the descriptions are for the purpose of fullydisclosing preferred embodiments of the technology for applying thefluidic network structure to apparel without placing limitationsthereon. Although the fluidic channel and dripping point geometries canvary greatly, the following examples are for the purpose of illustratingthe positioning of the fluidic channels and dripping points fordifferent applications. Therefore, the channel and dripping points inthe following figures have been simplified.

FIG. 34A and FIG. 34B illustrate how the fluidic channels 3400 on ashirt may be arranged so that the formation and dripping of the dropletsbecome unobvious. This embodiment may be useful for someone who findsmultiple droplets rolling down the outer surface of their garmentembarrassing or uncomfortable. In this design, the fluidic channels 3400are specifically arranged to remove the sweat from the body and drip itaway at the bottom of the shirt. The fluidic channels 3400 are extendedvertically to cover most of the shirt. The bottom transporting channels3402 are connected with the vertical fluidic channels and carry themoisture to the two dripping points 3404 at the bottom of the shirtwhere the moisture can be released and dripped away. The wind flowgenerated when the wearer is moving may facilitate the release of thedroplets as well.

The arrangement of the fluidic channels can be designed to specificallyremove the sweat generated on different sections of the human body. Indoing so, a garment with a fluidic network structure can remove themoisture from one location utilizing a minimum area of the garment whichmaintains comfort for the wearer over a long period of time (e.g. duringan exercise session or sports match). Since the liquid-repellent regionsare completely dry, the permeability of this region remains higher whichis beneficial for the evaporative cooling effect on the skin. Inaddition, the temperature of the liquid-repellent fabric remains higherwhich is beneficial for reducing the unpleasant chill that can beexperienced during and after a workout. According to one test, thetemperature of the dry fabric measured 7° C. warmer than a soakedfabric.

Referring to FIG. 35A, the front side of the shirt 3500 in this examplehas three main separated liquid-absorptive regions (the detailed fluidicchannel structure inside the region is not limited to the simplifieddesign shown here and can be any design that works best for a givenwearer or application). The middle region 3502 begins at the collar areaand extends to the bottom of the front side of the shirt. The left andright side regions 3504, 3506 begin at the shoulders of the shirt andcover the chest area of the human body. These three regions areseparated from each other by liquid-repellent regions 3508 that extendthroughout the fabric thickness. The center region 3502 of the garmentis for collecting and conducting the sweat running down from the headand neck to the bottom of the shirt without spreading it out to thechest or abdomen area. The other two regions 3504, 3506 are fortransporting the sweat generated on the chest area to the drippingpoints 3518, 3520 on the sides of the garment. The abdomen region 3508of the shirt remains mostly liquid-repellent since it is infrequently incontact with the torso in many postures during sports activities.

Referring to FIG. 35B, the back side of this example 3500 has an upperliquid-absorptive region 3510 and a middle liquid-absorptive region3512. The upper region 3510 is connected with the collar region on thefront side and extends down and across to the sides of the shirt. Themiddle region 3512 is located below region 3510 and covers the middleregion of the back and also wraps around the side of the shirt. The twoliquid-absorptive regions 3510, 3512 are separated by a liquid-repellentregion 3514 that penetrates through the fabric. The upperliquid-absorptive region 3510 collects the sweat mainly from the headand neck areas and the middle region 3512 removes the sweat from theupper back area of the body and channels the sweat to the sides of theshirt. The lower portion of the garment that covers the lower back/waistarea is left completely liquid-repellent since this section of the shirtinfrequently touches the skin during many workouts.

FIG. 36A and FIG. 36B illustrate another embodiment 3600 of a detailedliquid-absorptive channel 3602 configuration on a shirt following thegeneral region arrangement shown in the previous embodiment 3500. Theback of each channel can be partially liquid-repellent according to theprevious descriptions. The arrows indicate the direction of the fluidflow as well as the location of the dripping points 3612, 3614, 3616,3618, 3630, 3632.

Referring to FIG. 36A, the front side of the shirt in this embodiment3600 has three main liquid-absorptive regions. The left and rightliquid-absorptive channel chest regions 3606, 3608 are separated fromthe main liquid-absorptive channel 3610 by a liquid-repellent region3620, 3622. The main liquid-absorptive channel 3610 runs vertically downthe front side of the shirt and carries fluid from the head and neckregion 3604 to the two bottom dripping points 3612, 3614. The leftliquid-absorptive channel chest region 3606 and the rightliquid-absorptive channel chest region 3608 carry fluid from the chestto the dripping points 3616, 3618 on the side of the shirt. The abdomenregions of the front 3620, 3622 and back 3624 of the shirt remain mostlyliquid-repellent since these regions are infrequently in contact withthe torso in many postures during sports activities.

Referring to FIG. 36B, the back of the shirt has two main separatedliquid-absorptive regions 3626, 3628. The liquid-absorptive head/neckchannel region 3626 carries fluid from the head and neck to the sidedripping points 3630, 3632.

In the embodiment 3700 shown in FIG. 37A through FIG. 37C, the sleeves3706 of the shirt are incorporated into the fluidic network design shownin FIG. 36A and FIG. 36B. FIG. 37C shows a side view of the shirtembodiment 3700 with the liquid-absorptive channels 3702 running alongthe shoulder and down the upper arm area of the shirt. Fluid is carriedfrom the head and neck across the shoulder and down to the drippingpoint 3704 on the end of the sleeve.

In some situations, it may be advantageous to keep the fluid fromdripping off of the garment and onto a surface, for example in abasketball, badminton or racquetball game. For these situations, thedripping points at the end of the liquid-absorptive channel networks canbe connected to a liquid-absorptive panel which can hold the fluid (e.g.sweat), which can be removed to a desired location or held in the panelsto evaporate. FIG. 38A and FIG. 38B show a diagram of the front andback, respectively, of a shirt with a bottom liquid-absorptive panel3802 and two side liquid-absorptive panels 3804, 3806 and aliquid-absorptive channel network design that is identical to theexample 3600 previously described in FIG. 36A and FIG. 36B. As thesepanels are on the sides of the shirt, the wearer remains comfortableduring sports activity.

FIG. 38C is an image of the shirt described in FIG. 38A with theliquid-absorptive panel on the bottom 3802 shown collecting the sweat(dark color) from the wearer after exercise instead of dripping thesweat away. FIG. 38D is an image of the shirt described in FIG. 38A andFIG. 38B where the side panels are shown collecting the sweat from thewearer after exercise instead of dripping the sweat away. In bothimages, the majority of the shirt is shown as dry, except for theliquid-absorptive channels 3808 and side panel 3806.

In an alternative to the example described in FIG. 38A through FIG. 38D,the liquid-absorptive side panels 3804, 3806 can be constructed as amaterial that is different than the rest of the shirt. Also, theliquid-absorptive side panels 3804, 3806 and bottom liquid-absorptivepanel 3802 can be made detachable and replaced with a dry panel whenthey become saturated with fluid.

In another configuration of the previously described embodiment 3800,the absorbent panels can be reversible where they can be switchedbetween a panel with dripping points connected to the channel networkand the liquid-absorptive (non-dripping) panel. The wearer can choosethe appropriate mode of sweat management according to different needs ofthe activities.

The embodiment 3900 shown in FIG. 39A and FIG. 39B, has a front sidethat has a liquid-absorptive region 3902 which covers both the collarand chest area and extends to the side dripping points 3906, 3908 of theshirt while the abdomen region 3904 is kept liquid-repellent. The backside, shown in FIG. 39B, has the same liquid-absorptive region 3902covering both the collar and upper back area while the lower back area3904 remains liquid-repellent.

FIG. 40 shows a diagram 4000 of a fluidic channel network in the shapeof a tree pattern on a shirt following the simplified channel regionarrangement depicted in FIG. 39A. The crown region of the tree shapeconsists of several randomly distributed short fluidic channels 4002which carry fluid from the head, neck and chest regions down to thetrunk 4004 of the tree shape. The fluid then travels through the rootshaped fluidic channels 4006 and off of the shirt at the dripping points4008.

In another embodiment 4100, the front panel of the shirt has threeregions of liquid-absorptive channels separated by liquid-repellentregions as seen in FIG. 41A. This design can be useful when the garmentis being worn as a compression garment that fits tightly against thebody. The top liquid-absorptive channel region 4102 is connected withthe collar region of the shirt and carries fluid to the underarm areadripping points 4104, 4106. The center liquid-absorptive region 4108covers the chest area and carries fluid to the mid-abdomen side drippingpoints of the shirt 4110, 4112. The bottom-abdomen liquid-absorptiveregion 4114 covers the abdomen area and carries fluid to the lowerportion of the shirt to drip off the bottom.

The back panel of the shirt, shown in FIG. 41B, has 4 liquid-absorptiveregions separated by a liquid-repellent region. The topliquid-absorptive region 4116 carries fluid from the collar and shoulderregions of the shirt to the upper side dripping points 4118, 4120 of thegarment. The left 4122 and right 4124 center liquid-absorptive regionscover the upper back and carry fluid to the lower sides of the shirt tothe dripping points 4126, 4128. The gap between these two regions is theliquid-repellent region 4130 and keeps the middle regions dry withmaximum gas permeability for a cooling effect on the spine. The bottomliquid-absorptive region 4132 covers the lower back and waste area andcarries fluid to the bottom of the shirt.

In another embodiment, the garment configuration may incorporateliquid-absorptive regions that transport sweat away from temperaturesensitive areas on the body to reduce the post-chill feel afterexercise. Temperature sensitive areas are those regions that are moresensitive to temperature changes, including the spine, the front of thechest, below the breasts, the armpits, etc. The dryness of these areasafter exercise will reduce the unpleasant chill that wet fabric cancause after exercise. This garment configuration can require lessliquid-absorptive regions which can reduce big temperature drops onthese areas after exercise due to the evaporation cooling effect of thefabric. Alternatively, more liquid-absorptive regions can be arrangedover temperature sensitive areas to provide a stronger cooling feel overthese regions during exercise.

In another embodiment, the fluidic network structure may follow thegeometry or profile of the human body. The convex regions of the humanbody (e.g. chest, shoulder, and belly) can be covered withliquid-absorptive channels while the concave regions (e.g. lower back)of the human body can be left liquid-repellent or can also be coveredwith the liquid-absorptive channels. The gender of the wearer can alsoaffect the apparel design. The different body structure between malesand females can result in different regions being utilized fortransporting and removing sweat.

In another embodiment, the number of liquid-absorptive channels on agarment can be customized according to a specific wearer's body areasand perspiration rates. For the body regions where the wearer perspiresslowly, more liquid-repellent areas can be arranged in order to leave alimited amount of sweat to evaporate off of their skin for cooling. Fora wearer with a high perspiration rate, more liquid-absorptive channelscan be placed in a manner to use the fluidic transport mechanism(gravity, compression or surface tension forces) to remove the largervolume of sweat more quickly.

In another embodiment, a garment with a fluidic network structure can beutilized for pre-cooling a wearer before an activity or just cooling awearer in warm temperatures. The garment can be immersed in water beforethe wearer puts it on to provide a longer cooling effect for the wearer.Since the wet area of the garment can be limited, there is only a smallincrease in the weight of the garment. Moreover, the chilling feel ofthe garment can be controlled by adjusting the ratio of the wet area tothe dry area of the garment.

The position, number of liquid-absorptive channels, direction of thefluid flow, and liquid-repellant regions are not limited to the examplesin the present description. The configuration of the fluidic networkstructure can depend on how tight the garment is, the wearer's postureduring a particular activity, a desired esthetic, etc. Additionally, thefront and back sides of a shirt, etc. can be separated and the garmentcan be constructed to have only the front or the back side modified formoisture management.

FIG. 42A shows a diagram of an example fluidic network structure asapplied to a pair of shorts 4200. On the waist area of the short,fluidic channels 4202 can be constructed so that the sweat flowing downfrom the upper body during movement can be collected by the channels4202 on the waistband and transported to the sides of the short. Thesweat can then flow down to the edge of the fluidic channel structureand drip away at the dripping points 4204, 4206. FIG. 42B is an image ofthe front of the shorts shown in FIG. 42A. FIG. 42C is an image of theside of the shorts shown in FIG. 42A. The rest of the shorts 4108 can beleft completely liquid-repellent as the wearer may have underwear onunderneath the shorts. Without the fluidic channels on the waistband, alarge amount of sweat may soak the shorts, including the wearer'sunderwear.

FIG. 43A shows a diagram illustrating another version 4300 of thefluidic channel configuration as applied to a pair of shorts where thefluidic channels 4302 extend to the sides of the leg region.

FIG. 44 is a diagram illustrating another fluidic channel networkconfiguration on a pair of shorts 4400 where fluid-absorptive channels4402 cover the shorts to transport the sweat to the sides of the shortsand drip it away via the dripping points 4404, 4406. The circles 4408are an example of what the fluidic inlets might look like on the innerlayer of the shorts.

FIG. 45 shows a diagram of one embodiment 4500 of a sock with aliquid-absorptive fluidic network structure that has fluidic channels4502 that carry the sweat running down the leg to the sides of the sockand drip it away via dripping points 4504, 4506. The socks and shoes ofa wearer can become saturated during exercise not only because of thesweat generated by foot itself, but also from the sweat running down thelegs into the shoes. Incorporating a fluidic channel into socks canlargely reduce the body sweat running into the shoes, making the feetuncomfortable.

FIG. 46A shows a diagram of one embodiment 4600 of a headband with aliquid-absorptive fluidic network. The headband comprisesliquid-absorptive channels 4602 and liquid-repellent areas 4604. Theliquid-absorptive channels 4602 are arranged in a pattern that carriesthe sweat generated on the forehead to the two dripping points 4606,4608 on the sides of the face. The liquid-absorptive channels 4602 willprevent the sweat from running into eyes and burning. Following thegravity-driven flow principles, the liquid-absorptive channels 4602 willcontinuously remove the sweat to provide a cool and comfortable feel forthe wearer and will prevent the wearer from having to wipe theirforehead. FIG. 46B through FIG. 46D are images of the embodiment 4600shown in FIG. 46A. This headband is composed of the same fabric foractivewear and is much thinner and lighter compared to the conventionalterrycloth materials. It can be utilized as a standard sweatband forboth sports and industry applications. Such a sweat directing structurecan be integrated inside of a cap, helmet or other similar apparel.

When designing a fluidic network material for use with an exercisegarment, the human posture during a particular exercise should becarefully observed in order to provide the right fluidic channelconfiguration. For example, the arrangement of the fluidic channels 4702on a cycling garment 4700 should be very different from a running shirt,as the upper body of the bicycle rider will be nearly horizontal insteadof vertical most of the time, as shown in FIG. 47. The fluidic channels4702 on the back and front of the garment are mainly vertical when theathlete stays in the riding posture. The dripping point 4704 is at thebottom of the pants to ensure gravitational-force driven dripping.

FIG. 48A and FIG. 48B show diagrams of one embodiment 4800 of a tentwith a liquid-absorptive fluidic network on the interior. The fluidicnetwork structure is helpful for managing condensation that can be aproblem existing in current tent designs. When a camper stays in thetent for a prolonged period of time, the water vapor generated from thecamper's breath can condense on the inside surface of the tent. Themoisture can accumulate up to 1 L per 24 hours. With appropriate fluidmanagement using liquid-absorptive channels 4802, the condensed moisturewon't slide randomly down from the roof of the tent to form puddles ofwater around the floor of the tent. Instead, the moisture can bechanneled to a desired location or absorbed with a liquid-absorptive padand taken away from the tent. The fluidic network is also useful asapplied to tents to help keep the tent dry before the tent is packedaway. This avoids excess moisture and mold from growing in the packedtent.

In FIG. 48A, the fluidic network structure is arranged from the top 4804of the roof to the bottom 4806 of the tent. For simplicity ofillustration, only one section of the fluidic pattern is shown, however,the fluidic network would cover the four sections of the tent. Thefluidic network structure can reduce the volume of water thataccumulates on the roof, according to the principles previouslydescribed. In FIG. 48B, the tent has longer extended half-cylindricalfluid-absorptive channels 4802 and the interior fluidic networkarrangement is different. The short “ribs” 4808 of the channels aresymmetric around the top of the roof and the long transporting channels4810 are on the sidewalls 4812 with an angle towards the bottom end ofthe tent where the moisture can be collected.

From the description herein, it will be appreciated that that thepresent disclosure encompasses multiple embodiments which include, butare not limited to, the following:

1. An apparatus for managing fluid, the apparatus comprising: asubstrate having a first region with a first wettability and having asecond region with a second wettability; wherein the second region isadjacent to the first region; wherein the second wettability is greaterthan the first wettability; wherein the second region forms a fluidicchannel having a fluid flow direction; and wherein the fluidic channelis configured such that fluid moves along the fluidic channel by a forceapplied in the flow direction in response to fluid contacting thefluidic channel.

2. The apparatus of any preceding embodiment, wherein the force appliedis one or more of gravitational force, compression force, capillaryforce or surface tension force.

3. The apparatus of any preceding embodiment, further comprising: adripping point coupled to the fluidic channel; wherein the drippingpoint is positioned near the lowest gravitational point of the fluidicchannel; wherein the substrate is configured such that fluid collects atthe dripping point and drips off of the substrate; and wherein thedripping point is configured to slow down or speed up a rate at whichthe fluid drips off of the substrate.

4. The apparatus of any preceding embodiment, wherein the fluidicchannel is interrupted by a liquid-repellent gap configured forunidirectional fluid flow.

5. The apparatus of any preceding embodiment: wherein the firstwettability is liquid-repellent, creating a liquid-repellent region; andwherein the second wettability is liquid-absorptive, creating aliquid-absorptive region.

6. The apparatus of any preceding embodiment, wherein the fluidcontacting the fluidic channel is facilitated by a compression forcegenerated by the liquid-repellent region being in close contact with afluid producing surface.

7. The apparatus of any preceding embodiment, wherein the substratecomprises multiple contact angles within the liquid-absorptive region,creating a wettability gradient.

8. The apparatus of any preceding embodiment, wherein the substratecomprises multiple contact angles within the liquid-repellent region,creating a wettability gradient.

9. The apparatus of any preceding embodiment, wherein a plurality offluidic channels are configured to manage condensation.

10. The apparatus of any preceding embodiment, further comprising: athird region in the substrate having a third wettability; wherein thethird wettability is liquid-absorptive; wherein the third region ispositioned near the lowest gravitational point of the fluidic channel;and wherein the third region is configured to collect fluid and preventit from dripping off of the substrate.

11. The apparatus of any preceding embodiment, wherein the third regionis configured to be removable.

12. The apparatus of any preceding embodiment, wherein the substratefurther comprises: a first surface layer and a second surface layer;wherein the first surface layer comprises one or more fluidic channels;and a thickness of the substrate in between the first and second surfacelayers; wherein the fluidic channel penetrates the thickness of thesubstrate at one or more locations on the second surface layer; andwherein the fluidic channel is configured such that fluid moves from thesecond surface layer to the first surface layer along the fluidicchannel.

13. The apparatus of any preceding embodiment, further comprising: adripping point coupled to the fluidic channel; wherein the drippingpoint is positioned near the lowest gravitational point of the fluidicchannel; wherein the substrate is configured such that fluid collects atthe dripping point and drips off of the substrate; and wherein thedripping point is configured such that the dripping point is positionedonly on the second surface layer, preventing fluid from contacting thefirst surface layer as it drips off of the substrate.

14. The apparatus of any preceding embodiment, wherein a portion of thechannel that penetrates the thickness of the substrate is smaller at thesecond surface layer and gets larger as it reaches the first surfacelayer.

15. The apparatus of any preceding embodiment, wherein a layer ofliquid-repellant material is positioned on top of the first surfacelayer such that the fluidic channels are invisible when wet or dry.

16. The apparatus of any preceding embodiment, wherein the fluidicchannel extends past the second surface layer to form a supportstructure.

17. The apparatus of any preceding embodiment, wherein the fluidicchannel is a component of a garment.

18. The apparatus of any preceding embodiment, wherein a plurality offluidic channels form a design on the garment.

19. The apparatus of any preceding embodiment, wherein a plurality offluidic channels are configured in the garment to manage perspiration ona human body.

20. The apparatus of any preceding embodiment: wherein the garment is ashirt; wherein a first plurality of fluidic channels forms a neck regionin the shirt configured to transport perspiration away from a person'sneck to the bottom of the shirt where the perspiration drips off of theshirt; wherein a second plurality of fluidic channels forms one or morechest regions in the shirt configured to transport perspiration from aperson's chest to one or more sides of the shirt where the perspirationdrips off of the shirt; and wherein a third plurality of fluidicchannels forms one or more back regions in the shirt configured totransport perspiration from a person's chest to one or more sides of theshirt where the perspiration drips off of the shirt.

21. The apparatus of any preceding embodiment, wherein a fourthplurality of fluidic channels forms one or more sleeve regions in theshirt configured to transport perspiration from a person's head and neckto the bottom of the sleeve where the perspiration drips off of theshirt.

22. An apparatus for managing fluid, the apparatus comprising: asubstrate having a first liquid-absorptive region with a firstwettability and having a second liquid-absorptive region with a secondwettability; wherein the second liquid-absorptive region is adjacent tothe first liquid-absorptive region; wherein the second wettability isgreater than the first wettability; wherein the first and secondliquid-absorptive regions form a wettability gradient for fluidic flow;and wherein when fluid contacts the substrate, the fluid moves along thegradient from the first liquid-absorptive region to the secondliquid-absorptive region.

23. The apparatus of any preceding embodiment, wherein the substratecomprises multiple contact angles within the second liquid-absorptiveregion, creating a wettability gradient.

24. The apparatus of any preceding embodiment, wherein the substratecomprises multiple contact angles within the first liquid-absorptiveregion, creating a wettability gradient.

25. The apparatus of any preceding embodiment, wherein the fluidic flowin the second liquid-absorptive region is affected by one or more ofgravitational force, compression force, capillary force or surfacetension force.

26. An apparatus for managing fluid, the apparatus comprising: (a)

a plurality of fluidic channels; (b) each of the fluidic channelscomprising: (i) a substrate having a first region with a firstwettability and having a second region with a second wettability; (ii)wherein the second region is adjacent to the first region; (iii) whereinthe second wettability is greater than the first wettability; (iv)wherein the second region forms the fluidic channel having a fluid flowdirection; (v) wherein the fluidic channel is configured such that fluidmoves along the fluidic channel by a force applied in the flow directionin response to fluid contacting the fluidic channel; and (c) wherein theplurality of fluidic channels is arranged in a fluidic networkstructure.

27. A method for managing fluid, the method comprising: creating a firstregion with a first wettability in a substrate; and creating a secondregion with a second wettability in the substrate; wherein the secondwettability is greater than the first wettability; and wherein thesecond region forms a fluidic channel having a fluid flow direction; andconfiguring the fluidic channel such that fluid moves along the fluidicchannel by a force applied in the flow direction in response to fluidcontacting the fluidic channel.

28. The method of any preceding embodiment, wherein the force applied isone or more of gravitational force, compression force, capillary forceor surface tension force.

29. The method of any preceding embodiment, wherein the first region andthe second region are created using a printing process.

30. The method of any preceding embodiment, wherein the first region andthe second region are created using a knitting process.

Although the description herein contains many details, these should notbe construed as limiting the scope of the disclosure but as merelyproviding illustrations of some of the presently preferred embodiments.Therefore, it will be appreciated that the scope of the disclosure fullyencompasses other embodiments which may become obvious to those skilledin the art.

In the claims, reference to an element in the singular is not intendedto mean “one and only one” unless explicitly so stated, but rather “oneor more.” All structural, chemical, and functional equivalents to theelements of the disclosed embodiments that are known to those ofordinary skill in the art are expressly incorporated herein by referenceand are intended to be encompassed by the present claims. Furthermore,no element, component, or method step in the present disclosure isintended to be dedicated to the public regardless of whether theelement, component, or method step is explicitly recited in the claims.No claim element herein is to be construed as a “means plus function”element unless the element is expressly recited using the phrase “meansfor”. No claim element herein is to be construed as a “step plusfunction” element unless the element is expressly recited using thephrase “step for”.

TABLE 1 Pressure Pressure Pore Size (100% (~50% Weight Thickness(estimated) penetration) penetration) Structure Composition (g/m2) (mm)(μm) (Pa) (Pa) A Single-knit 92% polyester 168 0.508 98.4 740 250 Jersey8% spandex B Single-knit 92% polyester 187 0.772 40 >1000 650 Jersey 8%spandex C Interlock 100% 175 0.574 104 990 400 polyester

TABLE 2 Fabric patterned Improvement with fluidic (Patterned- channelsControl control)/control Wet pickup ratio 50% 188% 73% lighter when (WPU%) wet Vapor Permeability 1680 1340 25% more when saturated permeablewhen (g · m⁻²day⁻¹)^(†) wet Wet area ratio 43% 100% 57% more dry(outside) area Wet area  8% 100% 92% more dry ratio(inner) area Dryingtime(min)^(‡)  60  210 70% Faster ^(†)Experiment was conducted in 23° C.and 40% humidity ^(‡)Experiment was conducted in 25° C. and 37% humidity

TABLE 3 Water Weight Drying Weight (g) Increase Weight increase timeSample Before After (g) percent (%) (min)^(†) Patterned 0.57 1.32 ± 0.200.75 132.28 ± 35.58 110 Original 0.35 1.36 ± 0.13 1.01 288.57 ± 37.42210

What is claimed is:
 1. An apparatus for managing fluid, the apparatuscomprising: a substrate having a first region with a first wettabilityand having a second region with a second wettability; wherein the secondregion is adjacent to the first region; wherein the second wettabilityis greater than the first wettability; wherein the second region forms afluidic channel having a fluid flow direction; and wherein the fluidicchannel is configured such that fluid moves along the fluidic channel bya force applied in the flow direction in response to fluid contactingthe fluidic channel.
 2. The apparatus of claim 1, wherein the forceapplied is one or more of gravitational force, compression force,capillary force or surface tension force.
 3. The apparatus of claim 1,further comprising: a dripping point coupled to the fluidic channel;wherein the dripping point is positioned near the lowest gravitationalpoint of the fluidic channel; wherein the substrate is configured suchthat fluid collects at the dripping point and drips off of thesubstrate; and wherein the dripping point is configured to slow down orspeed up a rate at which the fluid drips off of the substrate.
 4. Theapparatus of claim 1, wherein the fluidic channel is interrupted by aliquid-repellent gap configured for unidirectional fluid flow.
 5. Theapparatus of claim 1: wherein the first wettability is liquid-repellent,creating a liquid-repellent region; and wherein the second wettabilityis liquid-absorptive, creating a liquid-absorptive region.
 6. Theapparatus of claim 5, wherein the fluid contacting the fluidic channelis facilitated by a compression force generated by the liquid-repellentregion being in close contact with a fluid producing surface.
 7. Theapparatus of claim 5, wherein the substrate comprises multiple contactangles within the liquid-absorptive region, creating a wettabilitygradient.
 8. The apparatus of claim 5, wherein the substrate comprisesmultiple contact angles within the liquid-repellent region, creating awettability gradient.
 9. The apparatus of claim 5, wherein a pluralityof fluidic channels are configured to manage condensation.
 10. Theapparatus of claim 1, further comprising: a third region in thesubstrate having a third wettability; wherein the third wettability isliquid-absorptive; wherein the third region is positioned near thelowest gravitational point of the fluidic channel; and wherein the thirdregion is configured to collect fluid and prevent it from dripping offof the substrate.
 11. The apparatus of claim 10, wherein the thirdregion is configured to be removable.
 12. The apparatus of claim 1,wherein the substrate further comprises: a first surface layer and asecond surface layer; wherein the first surface layer comprises one ormore fluidic channels; and a thickness of the substrate in between thefirst and second surface layers; wherein the fluidic channel penetratesthe thickness of the substrate at one or more locations on the secondsurface layer; and wherein the fluidic channel is configured such thatfluid moves from the second surface layer to the first surface layeralong the fluidic channel.
 13. The apparatus of claim 12, furthercomprising: a dripping point coupled to the fluidic channel; wherein thedripping point is positioned near the lowest gravitational point of thefluidic channel; wherein the substrate is configured such that fluidcollects at the dripping point and drips off of the substrate; andwherein the dripping point is configured such that the dripping point ispositioned only on the second surface layer, preventing fluid fromcontacting the first surface layer as it drips off of the substrate. 14.The apparatus of claim 12, wherein a portion of the channel thatpenetrates the thickness of the substrate is smaller at the secondsurface layer and gets larger as it reaches the first surface layer. 15.The apparatus of claim 12, wherein a layer of liquid-repellant materialis positioned on top of the first surface layer such that the fluidicchannels are invisible when wet or dry.
 16. The apparatus of claim 12,wherein the fluidic channel extends past the second surface layer toform a support structure.
 17. The apparatus of claim 1, wherein thefluidic channel is a component of a garment.
 18. The apparatus of claim17, wherein a plurality of fluidic channels form a design on thegarment.
 19. The apparatus of claim 17, wherein a plurality of fluidicchannels are configured in the garment to manage perspiration on a humanbody.
 20. The apparatus of claim 19: wherein the garment is a shirt;wherein a first plurality of fluidic channels forms a neck region in theshirt configured to transport perspiration away from a person's neck tothe bottom of the shirt where the perspiration drips off of the shirt;wherein a second plurality of fluidic channels forms one or more chestregions in the shirt configured to transport perspiration from aperson's chest to one or more sides of the shirt where the perspirationdrips off of the shirt; and wherein a third plurality of fluidicchannels forms one or more back regions in the shirt configured totransport perspiration from a person's chest to one or more sides of theshirt where the perspiration drips off of the shirt.
 21. The apparatusof claim 20, wherein a fourth plurality of fluidic channels forms one ormore sleeve regions in the shirt configured to transport perspirationfrom a person's head and neck to the bottom of the sleeve where theperspiration drips off of the shirt.
 22. An apparatus for managingfluid, the apparatus comprising: a substrate having a firstliquid-absorptive region with a first wettability and having a secondliquid-absorptive region with a second wettability; wherein the secondliquid-absorptive region is adjacent to the first liquid-absorptiveregion; wherein the second wettability is greater than the firstwettability; wherein the first and second liquid-absorptive regions forma wettability gradient for fluidic flow; and wherein when fluid contactsthe substrate, the fluid moves along the gradient from the firstliquid-absorptive region to the second liquid-absorptive region.
 23. Theapparatus of claim 22, wherein the substrate comprises multiple contactangles within the second liquid-absorptive region, creating awettability gradient.
 24. The apparatus of claim 22, wherein thesubstrate comprises multiple contact angles within the firstliquid-absorptive region, creating a wettability gradient.
 25. Theapparatus of claim 22, wherein the fluidic flow in the secondliquid-absorptive region is affected by one or more of gravitationalforce, compression force, capillary force or surface tension force. 26.An apparatus for managing fluid, the apparatus comprising: (a) aplurality of fluidic channels; (b) each of the fluidic channelscomprising: a substrate having a first region with a first wettabilityand having a second region with a second wettability; (ii) wherein thesecond region is adjacent to the first region; (iii) wherein the secondwettability is greater than the first wettability; (iv) wherein thesecond region forms the fluidic channel having a fluid flow direction;(v) wherein the fluidic channel is configured such that fluid movesalong the fluidic channel by a force applied in the flow direction inresponse to fluid contacting the fluidic channel; and (c) wherein theplurality of fluidic channels is arranged in a fluidic networkstructure.
 27. A method for managing fluid, the method comprising:creating a first region with a first wettability in a substrate; andcreating a second region with a second wettability in the substrate;wherein the second wettability is greater than the first wettability;and wherein the second region forms a fluidic channel having a fluidflow direction; and configuring the fluidic channel such that fluidmoves along the fluidic channel by a force applied in the flow directionin response to fluid contacting the fluidic channel.
 28. The method ofclaim 27, wherein the force applied is one or more of gravitationalforce, compression force, capillary force or surface tension force. 29.The method of claim 27, wherein the first region and the second regionare created using a printing process.
 30. The method of claim 27,wherein the first region and the second region are created using aknitting process.